A circuit breaker is a device that can be used to protect an electrical circuit from damage caused by an overload or a short circuit. If a power surge occurs in a circuit protected by the circuit breaker, for example, the breaker will trip. This will cause a breaker that was in the “on” position to flip to the “off” position, and will interrupt the electrical power leading from that breaker. By tripping in this way, a circuit breaker can prevent a fire from starting on an overloaded circuit, and can also prevent the destruction of the device that is drawing the electricity or other devices connected to the protected circuit.
A standard circuit breaker has a line and a load. Generally, the line receives incoming electricity, most often from a power company. This is sometimes referred to as the input into the circuit breaker. The load, sometimes referred to as the output, feeds out of the circuit breaker and connects to the electrical components being fed from the circuit breaker. A circuit breaker may protect an individual component connected directly to the circuit breaker, for example, an air conditioner, or a circuit breaker may protect multiple components, for example, household appliances connected to a power circuit which terminates at electrical outlets.
A circuit breaker can be used as an alternative to a fuse. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. When the power to a circuit shuts down, an operator can inspect the electrical panel to see which breaker has tripped to the “off” position. The breaker can then be flipped to the “on” position and power will resume.
In general, a circuit breaker has two contacts located inside of a housing. Typically, the first contact is stationary, and may be connected to either the line or the load. Typically, the second contact is movable with respect to the first contact, such that when the circuit breaker is in the “off,” or tripped position, a gap exists between the first and second contact, and the line is disconnected from the load.
In some applications, it is desirable to operate a circuit breaker remotely. For example, an operator may typically trip a circuit breaker manually to de-energize a protected circuit so that it can be inspected or serviced. However in some circuits, operating the breaker can produce a dangerous arc, creating a safety hazard for the operator. In still other circuits, the circuit breaker may be located in a confined or hazardous environment. In these situations, it is beneficial to operate the circuit breaker remotely. In other applications, such as in large office buildings, it may be desirable, for example, to automatically trip circuits powering large banks of overhead lights, such that entire floors or sections of floors can be automatically shut down in response to timed signals at night without requiring that each individual light switch have a timer.
Known approaches to remotely controlling circuit breakers include incorporating a mechanism into the circuit breaker which can intentionally trip the circuit breaker mechanism and/or reset it. Examples of such mechanisms are solenoids or motors used to activate the trip mechanism, and solenoids or motors which are used to reset the circuit breaker by rearming the trip mechanism, such as by physically moving the switch handle using a solenoid or other motor or mechanism that can be remotely operated.
However, the lifespan of a solenoid employed to reset a circuit breaker using the switching handle may be limited. In some cases, the re-arming solenoid may wear out or otherwise fail far before the other components of the circuit breaker. This can require an unacceptably premature replacement of the entire circuit breaker as a unit, increasing costs.
In order to increase the number of cycles that such circuit breaker units can endure before failure, it would be conceivable to increase the robustness of the solenoid. However, this may increase the costs, power consumption, and/or size of the solenoid beyond acceptable limits.
What is desired therefore, is a circuit breaker featuring a replaceable re-arming solenoid which addresses these and other disadvantages.